Table 1. Relaxed and global clock average age estimates (in Mya) for bilaterians and the tree root.

		Simulations
	Clock	Variable rates	Constant rate
Bilateria	Relaxed	692 ± 6 (119 ± 4)	706 ± 7 (52 ± 6)
	Global	864 ± 9 (22 ± 0.4)	700 ± 7 (35 ± 5)
Root	Relaxed	1,083 ± 15 (308 ± 14)	1,122 ± 11 (89 ± 8)
	Global	1,541 ± 14 (41 ± 1)	1,079 ± 8 (54 ± 7)

Divergence times are computed on 30,399-aa-long data for 36 taxa, simulated under variable (autocorrelated) or constant rates of evolution, by using either a relaxed or a global molecular clock. Expected (simulated) ages are 695 Mya for bilaterians and 1,085 Mya for the root. The 95% credibility interval widths are given in parentheses. All values are averages ± SE of 10 replicates.